Semileptonic Branching Ratios and Moments Giuseppe Della Ricca

Semileptonic Branching Ratios and Moments Giuseppe Della Ricca University and INFN – Trieste, Italy 9 th International Conference on B Physics at Hadron Machines October 14 -18, 2003 – Pittsburgh, PA, USA

BEAUTY’ 03 – October 14 -18, 2003 Motivations l- • semileptonic decays are – relatively simple theoretically at parton level – accessible experimentally – sensitive to quark couplings to W± (i. e. CKM matrix elements |Vub| and |Vcb|) b W nl u, c Vub, cb – probe the dynamics of the decay – probe the impact of strong interactions • two possible approaches – exclusive measurements • need form-factors to describe the transition of the B meson to a lighter one – inclusive measurements • need OPE and b-quark mass to extract |Vxb| from the total rate Giuseppe Della Ricca – Semileptonic BRs and Moments 2

BEAUTY’ 03 – October 14 -18, 2003 Target in naïve spectator picture the process is analogous muon decay to but QCD (perturbative and non-perturbative) corrections are needed to extract weak decay physics comparison of results from different measurements provides a test of the consistency of OPE predictions and of underlying assumptions use many different approaches/techniques CKM’ 02 @ CERN Giuseppe Della Ricca – Semileptonic BRs and Moments 3

BEAUTY’ 03 – October 14 -18, 2003 Framework sin 2 Bd mixing: md kaon decays: εK Bs mixing: ms / md b ul : |Vub| D*l : |Vcb| measurements of |Vub| and |Vcb| provide stringent tests of the unitarity triangle Giuseppe Della Ricca – Semileptonic BRs and Moments 4

BEAUTY’ 03 – October 14 -18, 2003 Outline Vcb or Vub • exclusive measurements – – – BR(B e ) [Ba. Bar] BR(B l ), BR(B “ ”l ), BR(B l ) [Ba. Bar, Belle, Cleo] BR(B D*l ) [Ba. Bar] BR(B l ) [Cleo] far too much interesting BR(B D**0 l X) [Opal] material to include in 20 min [apologies in advance] • inclusive measurements – <Mxn>, <Eln> in B Xcl [Ba. Bar, Cleo, Delphi] – BR(B Xul ) [Ba. Bar] – BR(B Xul ) [Belle] my own selection of recent result Giuseppe Della Ricca – Semileptonic BRs and Moments 5

BEAUTY’ 03 – October 14 -18, 2003 BR(B 0 +e- ) [1] signal (ISGW 2) crossfeed b ue downfeed HILEP (ISGW 2+De. Fazio Neubert) b ce (HQET + Goity Roberts) M HILEP E HILEP: 2. 3< Eelectron<2. 7 Ge. V (large continuum backgrounds) LOLEP: 2. 0< Eelectron<2. 3 Ge. V (large b ce backgrounds) (B 0 -e+ ) =2 (B+ 0 e+ ) M E (B 0 -e+ ) = 2 (B+ 0 e+ )= (B+ e+ ) (isospin-constrained average of and 0) Giuseppe Della Ricca – Semileptonic BRs and Moments 6

BEAUTY’ 03 – October 14 -18, 2003 BR(B 0 +e- ) [2] extrapolate partial branching fraction to entire lepton-energy spectrum using five different form-factor calculations combined result: unweighted mean theoretical error on the combined result: full spread seen between the different form-factors combined result (unweighted mean): PRL 90 (2003) 181801 BR=(3. 29 0. 42 0. 47 0. 55 ) x 10 -4 Giuseppe Della Ricca – Semileptonic BRs and Moments 7

BEAUTY’ 03 – October 14 -18, 2003 BR(B 0 l , “ 0”l , l ) very high purity but small statistics loose cuts: small model dependence 0 “ 0” : 0. 65<m <0. 95 Ge. V/c 2 “ 0” BR(B 0 l ) = (0. 78 0. 32 0. 13 ) x 10 -4 BR(B “ 0”l ) = (0. 99 0. 37 0. 19 ) x 10 -4 BR(B l ) = (2. 20 0. 92 0. 57 ) x 10 -4 new CLEO results: see next talk ! Giuseppe Della Ricca – Semileptonic BRs and Moments preliminary 8

BEAUTY’ 03 – October 14 -18, 2003 B D*l : motivations B D*l represents 10% (5% e +5% channel) of the total B 0 decays, so a precise understanding of this decay improves the overall knowledge of the B branching ratios K the study of the differential decay rate can be used to extract |Vcb| D*± D 0 ± D 0 K , Ks , K 0, K d. M [= M(D*)-M(D 0)] used to fit signal and background components (except D**) ps D 0 p B 0 e/ constrained vertex fit on D 0 decay products, soft pion and lepton data control samples are used to estimate the background components (72 samples) Giuseppe Della Ricca – Semileptonic BRs and Moments 9

BEAUTY’ 03 – October 14 -18, 2003 Background characterization: fit to d. M [= M(D*)-M(D 0)] continuum from data control samples fake lepton Giuseppe Della Ricca – Semileptonic BRs and Moments uncorrelated fake D* 10

BEAUTY’ 03 – October 14 -18, 2003 Separation of D** component once other backgrounds are estimated from the global fit, B 0(+) D*Xl events are separated using the angle between the B 0 and the D*l direction. can be written as: p. B p q. BY pmiss qmin p. Y = p + plept electrons-K mode D*l (73. 5%) D**l (7. 5%) Real D*, Fake (0. 3%) Uncorrelated D* (6. 2%) Correlated D*(1. 5%) Continuum D*(3. 2%) Fake D*(7. 75%) if B 0 D*l if B 0(+) D*Xl D** shape different from the D* one fitted in each D 0 mode and e/ subsample Giuseppe Della Ricca – Semileptonic BRs and Moments 11

BEAUTY’ 03 – October 14 -18, 2003 Results for BR(B D*l ) hep-ex/0308027 BR(B 0 D*-l+ )= (4. 69± 0. 02 stat. data ± 0. 02 stat. MC ± 0. 24 syst. data)% comparison with other results Giuseppe Della Ricca – Semileptonic BRs and Moments 12

BEAUTY’ 03 – October 14 -18, 2003 Orbitally excited D mesons (D**) • D**0 are L=1 orbitally excited charm mesons – narrow Jq= 3/2, Jp=1+, 2+ states (D 10, D 2*0) – wide Jq= 1/2, Jp=0+, 1+ states (not visible with statistics) motivation • investigate the difference between measured inclusive and exclusive semileptonic branching ratios • reduce uncertainty in |Vcb| • test HQET predictions Giuseppe Della Ricca – Semileptonic BRs and Moments 13

BEAUTY’ 03 – October 14 -18, 2003 Method • identify high p lepton ( , e) – high efficiency and purity for p > 3 Ge. V/c, pe> 2 Ge. V/c • exclusively reconstruct D**0 D*+ **D 0 +slow K- +( + -) • background cuts to remove fake **- ( from fragmentation) – main background from decays plus fake **– ANN (p, p. T, d 0/σd 0) to select **- Giuseppe Della Ricca – Semileptonic BRs and Moments 3 mm 14

BEAUTY’ 03 – October 14 -18, 2003 D**0 – D*+ mass difference combine D 0→ K and K 3 channels to reduce uncertainty due to background unbinned ML fit to determine number of D 1 and D 2* events (B. -W. Gaussian) number of wrong sign and right sign background events fit simultaneously Giuseppe Della Ricca – Semileptonic BRs and Moments CERN-EP-2002 -094 15

BEAUTY’ 03 – October 14 -18, 2003 Bo & B+ semileptonic decays accurate, separate BRsl for Bo & B+, tagged by fully reconstructing one B BR(B+ Xl )/B(B 0 Xl )=1. 14 0. 01 preliminary BRsl(%) sl(ns-1) Bo B+ 10. 32 0. 29 67. 0 2. 8 11. 77 0. 26 0. 32 71. 1 2. 5 ½(Bo+B+) 11. 19 0. 20 0. 31 69. 0 1. 9 Y(4 S) 10. 89 0. 24 67. 7 1. 8 Giuseppe Della Ricca – Semileptonic BRs and Moments sl(B+)/ sl(Bo)=1. 063± 0. 038 16

BEAUTY’ 03 – October 14 -18, 2003 Semileptonic B decays average BRsl on Y(4 S), use high momentum lepton to tag flavor of 1 st B CLEO BR(B Xe )= (10. 89 0. 08 stat 0. 33 syst)% preliminary, EPS’ 03 272 LEP(most recent EW fit)=(10. 59 0. 22)% 10. 76% at Y(4 S) Giuseppe Della Ricca – Semileptonic BRs and Moments 17

BEAUTY’ 03 – October 14 -18, 2003 Parameters of HQE parameterization of decay rate in terms of Operator Product Expansion in HQET in powers of as(mb) 0 and /m. B: , 1, 2, are non-perturbative parameters pole mass expansion · 1 : · 2 : (-) kinetic energy of the motion of the b-quark chromo-magnetic coupling of b-quark spin to gluon (from B*-B mass difference, 2=0. 12 Ge. V 2) · = m. B – mb + ( 1 - 3 2)/2 m. B + … + additional parameters enter at higher orders ( 1, 2, t 1, t 2, t 3, t 4 ) use theoretical estimates – 1/m. B 3 Giuseppe Della Ricca – Semileptonic BRs and Moments 18

BEAUTY’ 03 – October 14 -18, 2003 OPE parameter extraction first derivations of OPE parameters from spectral moments used the pole mass expansion and photon energy spectrum in B Xs , hadronic mass spectrum and lepton energy spectrum in B Xcl E PRL 87 (2001) 251807 MX 2 PRL 87 (2001) 251808 Giuseppe Della Ricca – Semileptonic BRs and Moments El PRD 67 (2001) 072001 19

BEAUTY’ 03 – October 14 -18, 2003 Moments of lepton energy spectrum and hadronic mass spectrum in Z bb events Bd 0 D**l decays exclusively reconstructed * in three channels: D** D*+ -, D 0 +, D+ D** Z qq B D B l l- K + * - D 0 + 3 mm first measurements of moments performed at LEP exploiting advantage of Z 0 kinematics signal: good secondary vertex reconstruction and signal/background separation bb / hadrons 22% EB 0. 7 Ebeam 30 Ge. V Giuseppe Della Ricca – Semileptonic BRs and Moments 20

BEAUTY’ 03 – October 14 -18, 2003 Hadronic mass spectrum in B D**l D** D*+ - D** D 0 + D** D+ - M = M(D(*) ) - M(D(*)) distributions fitted including contributions of resonant (narrow, broad) and non resonant states, D*Xl floating BR(B 0 D**l )=(2. 7 0. 2) % DELPHI’ 03 -28 Giuseppe Della Ricca – Semileptonic BRs and Moments 21

BEAUTY’ 03 – October 14 -18, 2003 Interpretations moments of hadronic mass spectrum and of lepton energy spectrum are sensitive to the non -perturbative parameters of the Heavy Quark Expansion. at order 1/mb 2 , 1, 2 ( 2 0. 12 Ge. V 2) , at order 1/mb 3 1, 2, 1 -4 two possible approaches: 1) pole mass expansions (Falk, Luke, Gambino) 2) running quark masses (Bigi, Shifman, Uraltsev, Vainshtein) Giuseppe Della Ricca – Semileptonic BRs and Moments 22

BEAUTY’ 03 – October 14 -18, 2003 multi-parameter fit: 1(Ge. V 3) 1(Ge. V 2) Pole mass scheme (Ge. V) = 0. 542 + 0. 065 fit+ 0. 090 sys Ge. V 1=-0. 238 + 0. 055 fit+ 0. 030 sys. Ge. V 2 1= 0. 030 + 0. 028 fit+ 0. 010 sys. Ge. V 3 2= 0. 066 + 0. 025 fit + 0. 192 sys. Ge. V 3 M 1(Mx) M 2(Mx) M 3(Mx) M 1(El) M 2(El) M 3(El) (Ge. V) good consistency of all measurements ( 2/d. o. f. =0. 4) results compatible with CLEO similar results with mb 1 S- 1 formalism applied to CLEO and DELPHI data (C. W. Bauer, Z. Ligeti, M. Luke, A. V. Manohar hep-ph/0210027) Giuseppe Della Ricca – Semileptonic BRs and Moments 23

BEAUTY’ 03 – October 14 -18, 2003 Non-perturbative parameter extraction makes use of low scale running quark masses and does not rely on a 1/m c expansion mb( ), mc( ) are independent parameters and two operators only contribute to 1/mb 3 corrections : D 3, LS 3 first applied to fit DELPHI data – multi-parameter 2 fit to first three moments of lepton energy spectra and hadronic mass spectra (higher moments used to get sensitivity to 1/mb 3 parameters) – use expressions for non-truncated lepton spectra – simultaneous use of leptonic and hadronic moments in order to leave enough free parameters in the fit Phys. Lett. B 556 (2003) 41 Giuseppe Della Ricca – Semileptonic BRs and Moments 24

BEAUTY’ 03 – October 14 -18, 2003 M 1(Mx) M 2(Mx) M 3(Mx) M 1(El) M 2(El) M 3(El) 2 (Ge. V 2) r. D 3 (Ge. V 3) Kinetic mass scheme 4 -parameter fit input constraints: G 2= 0. 35 +0. 05 Ge. V 2 LS 3= -0. 15 +0. 15 Ge. V 3 mc= 1. 05 0. 30 Ge. V mb= 4. 57 0. 10 Ge. V mb (Ge. V) mb, kin (1 Ge. V)= mc, kin (1 Ge. V)= 2 (1 Ge. V) = D 3 (1 Ge. V) = equivalent to that derived from E in B Xs 4. 570 +0. 082 fit +0. 010 sys Ge. V 1. 133 +0. 134 fit +0. 030 sys Ge. V 0. 382 +0. 070 fit+0. 030 sys Ge. V 2 0. 089 +0. 039 fit+0. 010 sys Ge. V 3 good consistency of all measurements ( 2/d. o. f. =0. 9) within present accuracy no need to introduce higher order terms to establish agreement with data Giuseppe Della Ricca – Semileptonic BRs and Moments 25

BEAUTY’ 03 – October 14 -18, 2003 Generalized energy moments hep-ex/0212051 using ratios of truncated lepton spectra (Gremm et al. PRL 77 20 ’ 96) 1 s theoretical ellipse = 0. 39± 0. 03 stat± 0. 06 sys± 0. 12 th Ge. V 1=-0. 25± 0. 02 stat± 0. 05 sys± 0. 14 th Ge. V 2 Giuseppe Della Ricca – Semileptonic BRs and Moments parameters extracted from lepton spectra are in agreement with those extracted from MX 2 and E 26

BEAUTY’ 03 – October 14 -18, 2003 Hadronic mass moments [1] ~ <MX> ~ measured MX differs from true MX for each interval in MX, full detector simulation gives < MX> and <MX> ~ calibration curves applied to data: no model dependence ! non-res D** D* D <MX>TRUE <MX> <MX 2 -mb 2> pmin* dependence study pmin* Giuseppe Della Ricca – Semileptonic BRs and Moments pmin* 27

BEAUTY’ 03 – October 14 -18, 2003 Hadronic mass moments [2] <MX 2> fit OPE_ for <MX 2> to data and extract the two leading HQE parameters and 1 (MS scheme) all correlations taken into account CLEO b s it f PE O OPE prediction using CLEO data only <Mx 2> and <E > from b s pmin* all hadron mass moments are consistent (overlap from bands and BABAR ellipse) but 2=1 contour does not overlap with <E > band from CLEO b s Giuseppe Della Ricca – Semileptonic BRs and Moments 28

BEAUTY’ 03 – October 14 -18, 2003 Hadronic mass moments [3] extraction of mb 1 s, and 11 s from a fit to the HQE in the 1 s mass scheme (O(1/mb 3) parameters are fixed in the fit) 2=1 contour of hadron moments and lepton moments do not overlap indication for large O(1/mb 3) corrections, duality violation, or maybe even more …? hep-ex/0307046 Giuseppe Della Ricca – Semileptonic BRs and Moments 29

BEAUTY’ 03 – October 14 -18, 2003 Hadronic mass moments the neutrino 4 -vector is inferred using the detector hermeticity <M 2 X - M 2 D>El>1. 0 Ge. V = 0. 456± 0. 014± 0. 045± 0. 109 (Ge. V/c 2)2 <M 2 X - M 2 D>El>1. 5 Ge. V = 0. 293± 0. 012± 0. 033± 0. 048 (Ge. V/c 2)4 Giuseppe Della Ricca – Semileptonic BRs and Moments hep-ex/0307081 30

BEAUTY’ 03 – October 14 -18, 2003 Summary • Huge efforts/progress in this area !! • Large theoretical progress over the last decade (HQET & OPE) • Fully reconstructed B meson recoil tag, neutrino reconstruction • Many complementary observables • Inclusive studies yield crucial informations for Heavy Quark physics, even for exclusive decays Giuseppe Della Ricca – Semileptonic BRs and Moments 31

BEAUTY’ 03 – October 14 -18, 2003 Start of Backup Slides Giuseppe Della Ricca – Semileptonic BRs and Moments 32

BEAUTY’ 03 – October 14 -18, 2003 The Ba. Bar detector 1. 5 T solenoid Čerenkov Detector (DIRC) 144 quartz bars 11000 PMTs e- (9 Ge. V) Instrumented Flux Return iron/RPCs (muon/neutral hadrons) SVT: SVT+DCH: DIRC: EMC: Electro. Magnetic Calorimeter 6580 Cs. I(Tl) crystals e+ (3. 1 Ge. V) Drift CHamber 40 stereo layers Silicon Vertex Tracker 5 layers, double sided strips 97% efficiency, 15 m z hit resolution (inner layers, tracks) (p. T)/p. T = 0. 13 % p. T + 0. 45 % K- separation 4. 2 @ 3. 0 Ge. V/c >3. 0 @ 4. 0 Ge. V/c E/E = 2. 3 % E-1/4 1. 9 % Giuseppe Della Ricca – Semileptonic BRs and Moments 33

BEAUTY’ 03 – October 14 -18, 2003 The BELLE detector Aerogel Cherenkov cnt. n=1. 015~1. 030 SC solenoid 1. 5 T 3. 5 Ge. V e+ Cs. I(Tl) 16 X 0 TOF counter 8 Ge. V e- Central Drift Chamber small cell +He/C 2 H 5 Si vtx. detector 3 lyr. DSSD / KL detection 14/15 lyr. RPC+Fe Giuseppe Della Ricca – Semileptonic BRs and Moments vtx xy, z 55 m @1 Ge. V mom pt/pt=0. 19 pt (+) 0. 34 % E E/E~1. 8% @E=1 Ge. V PID: ACC+TOF+d. E/dx(CDC) e~90%, ~6% up to 3 Ge. V e-id: e>90%, ~0. 3% (>1 Ge. V) -id: e>90%, <2% (>1 Ge. V) [e=efficiency, =fake rate] 34

BEAUTY’ 03 – October 14 -18, 2003 The CLEO detector Giuseppe Della Ricca – Semileptonic BRs and Moments 35

BEAUTY’ 03 – October 14 -18, 2003 The DELPHI detector Giuseppe Della Ricca – Semileptonic BRs and Moments 36

BEAUTY’ 03 – October 14 -18, 2003 The OPAL detector Giuseppe Della Ricca – Semileptonic BRs and Moments 37

BEAUTY’ 03 – October 14 -18, 2003 Inclusive b cl • rather than focusing on one hadronic final state, sum over all states and compare to quark level calculation • relies on assumption of quark-hadron duality • constrain theory parameters and test consistency Giuseppe Della Ricca – Semileptonic BRs and Moments 38

BEAUTY’ 03 – October 14 -18, 2003 Inclusive BR(B Xc l- ) and t. B Y(4 S) BR(B Xc l- ) = (10. 83 0. 25) x 10 -2 t. B = (1. 598 0. 01) ps B Xc l- = 0. 446 (1 0. 023 0. 007)x 10 -10 Me. V LEP BR(B X l- ) = (10. 59 0. 22) x 10 -2 BR(B Xu l- ) = ( 0. 17 0. 05) x 10 -2 BR(B Xc l- ) = (10. 42 0. 26) x 10 -2 tb = (1. 573 0. 01) ps B Xc l- = 0. 436 (1 0. 022 0. 014)x 10 -10 Me. V word average B Xcl- = 0. 441 (1 0. 018) x 10 -10 Me. V Giuseppe Della Ricca – Semileptonic BRs and Moments 39

BEAUTY’ 03 – October 14 -18, 2003 Reconstruction and cuts D*/D 0 are reconstructed in the following modes: decay mode BR (%) D*± D 0 ± 67. 7 ± 0. 5 D 0 K 3. 80 ± 0. 09 D 0 Ks 2. 96 ± 0. 18 D 0 K 0 13. 1 ± 0. 9 D 0 K 7. 46 ± 0. 31 Giuseppe Della Ricca – Semileptonic BRs and Moments 40

BEAUTY’ 03 – October 14 -18, 2003 Moments of lepton energy spectrum and hadronic mass spectrum in Z bb events large momentum of b-hadrons (EB ~30 Ge. V) gives sensitivity to full lepton energy spectrum in B rest frame: measure first, second and third moment lepton spectrum in B Xc l- e+ background subtracted B system reconstructed from lepton+neutrino+charm vertex lepton boosted in B rest frame p (Ge. V/c) Giuseppe Della Ricca – Semileptonic BRs and Moments DELPHI’ 03 -28 41

BEAUTY’ 03 – October 14 -18, 2003 Results for Mn <mn. H>= p. D mn. D +p. D* mn. D* + (1 -p. D* )<mn. D**> moments of the hadronic mass M 1= <m 2 H - m 2 D> = 0. 647± 0. 046± 0. 093 (Ge. V/c 2)2 M 2= <(m 2 H - m 2 D)2> = 1. 98± 0. 23± 0. 29 (Ge. V/c 2)4 measured M 2’=<(m 2 H- <m 2 H>)2> = 1. 56± 0. 18± 0. 17 (Ge. V/c 2)4 M 3’=<(m 2 H- <m 2 H>)3> = 4. 05± 0. 74± 0. 31 (Ge. V/c 2)6 moments of the lepton energy spectrum <El*> = 1. 383± 0. 012± 0. 009 Ge. V DELPHI’ 03 -28 unfolded spectrum <(El*-<El*>)2> = 0. 192± 0. 005± 0. 008 Ge. V 2 <(El*-<El*>)3> =-0. 029± 0. 005± 0. 006 Ge. V 3 Giuseppe Della Ricca – Semileptonic BRs and Moments 42

BEAUTY’ 03 – October 14 -18, 2003 Lepton endpoint from the partial branching ratio with fu from CLEO (b s measurement) Electron Momentum [Ge. V/c] hep-ex/0207081 Giuseppe Della Ricca – Semileptonic BRs and Moments 43

BEAUTY’ 03 – October 14 -18, 2003 Hadronic moments - info Giuseppe Della Ricca – Semileptonic BRs and Moments 44

BEAUTY’ 03 – October 14 -18, 2003 End of Backup Slides Giuseppe Della Ricca – Semileptonic BRs and Moments 45